In shotblasting, it is important to uniformly distribute the projected grainy material on the surface of a product. Therefore, to indicate a degree of uniform distribution in shotblasting, a dent rate (coverage) is used, which is a ratio to an evaluation area of a shot blasted surface of a product, which area is a part of the shot blasted surface and is an area arbitrarily predetermined for evaluation, of the total area of dents created in the area. Moreover, in many cases the work to set, or determine, the shotblast processing condition to achieve a target coverage for a product when it is shot blasted temporarily sets a shotblast processing condition based on current experiences; carries out shotblasting under the condition; examines the shot blasted surface of the product to see dents in the surface; and measures the coverage, to narrow the condition.
By the way, conventionally there are two mainstream methods for measuring the dent rate, namely, a standard measuring method and a summary measuring method. The standard measuring method is to enlarge an arbitrary evaluation area of a shot blasted product by a microscope; take a photograph of the area in a 20–50 times enlarged scale; cut away the dented parts or untreated parts from the area; and obtain the dent rate from the percentage thereof by weight. The summary measuring method is to observe a shot blasted surface of the product by an observation apparatus such as a loupe with a 20–50 times magnifying power or a stereoscopic microscope; and compares the observed surface with reference photographs for comparison, to judge its rough dent rate value. And, the summary measuring method is mainly used for the reasons for the measurement frequency, the man-hours, etc.
However, though in the summary measuring method the reference photographs are made for their dent rates by using the standard measurement method, it is difficult in some products to judge if a part of them is dented or untreated. Further, in the standard measurement method itself there is a possibility to cause a dispersion due to the individual variations, and the dent rate must be measured by actually carrying out shotblasting for products to determine the shotblast processing condition. Moreover, because the area, the size, and the depth per dent change due to the shotblast processing condition, the hardness and the particle size of the projection material, the difference of the hardness between the product and the projection material, etc., it is necessary to make many reference photographs for each product. Additionally, the dent rate for a processed surface in a shotblasting processing that aims to decrease wear-out by fluid lubrication may be extremely low, and hence the range of the dent rates by the reference photographs must be increased.
This invention has been conceived in view of those circumstances. The main purpose of the invention is to provide a method and a system for simulating drawing a dent rate and a dent distribution diagram of a product by a computer, by giving an arbitrary dent producing condition and a shotblast processing condition in shotblasting.
A further purpose of the invention is to provide a method for setting a processing condition in shotblasting to obtain an arbitrary dent producing condition, a shotblast processing condition, and a target dent rate for a product in shotblasting and to provide a shotblasting device that uses the setting method.